//响应头的设置
module.exports = async (ctx,next) => {
    const contentType = 'application/json; charset=utf-8';
    ctx.set('Content-Type', contentType);
    ctx.set('Access-Control-Allow-Origin', '*');
    ctx.set('Access-Control-Allow-Methods', 'OPTIONS, GET, PUT, POST, DELETE');
    await next();
}